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#include "codeeditor.h"

#include <QPainter>
#include <QTextBlock>

//![constructor]

CodeEditor::CodeEditor(QWidget *parent) : QPlainTextEdit(parent)
{
    lineNumberArea = new LineNumberArea(this);

    connect(this, &CodeEditor::blockCountChanged, this, &CodeEditor::updateLineNumberAreaWidth);
    connect(this, &CodeEditor::updateRequest, this, &CodeEditor::updateLineNumberArea);
    connect(this, &CodeEditor::cursorPositionChanged, this, &CodeEditor::highlightCurrentLine);

    updateLineNumberAreaWidth(0);
    highlightCurrentLine();

    QFont font;
    font.setFamily("Monospace");
    // font.setFixedPitch(true);
    // font.setPointSize(10);
    this->setFont(font);
    this->lineNumberArea->setFont(this->font());

    this->setTabStopDistance(2 * fontMetrics().horizontalAdvance(' '));

    highlighter = new Highlighter(this->document());
}

void CodeEditor::moveCursorToLine(uint32_t line)
{
    // QList<QTextEdit::ExtraSelection> extraSelections;

    // QTextEdit::ExtraSelection s;
    // s.format.setBackground(Qt::yellow);
    // s.format.setProperty(QTextFormat::FullWidthSelection, true);

    // s.cursor = this->textCursor();
    // s.cursor.movePosition(
    //             QTextCursor::Start, QTextCursor::MoveAnchor, 1);
    // s.cursor.movePosition(QTextCursor::Down, QTextCursor::MoveAnchor, line - 1);
    // extraSelections.append(s);

    // this->setExtraSelections(extraSelections);

    // this->setTextCursor(s.cursor);

    auto c = this->textCursor();
    c.movePosition(
                QTextCursor::Start, QTextCursor::MoveAnchor, 1);
    c.movePosition(QTextCursor::Down, QTextCursor::MoveAnchor, line - 1);
    this->setTextCursor(c);
}

//![constructor]

//![extraAreaWidth]

#include <QDebug>
int CodeEditor::lineNumberAreaWidth()
{
//    int digits = 1;
//    int max = qMax(1, blockCount());
//    while (max >= 10) {
//        max /= 10;
//        ++digits;
//    }

//    int space = 3 + fontMetrics().horizontalAdvance(QLatin1Char('9')) * digits;
//    int space = 2 * fontMetrics().horizontalAdvance(' ') * digits;
//    qDebug() << "blockcount:" << blockCount();
    int space = fontMetrics().horizontalAdvance(QString::number(qMax(1, blockCount())));

    return space;
}

//![extraAreaWidth]

//![slotUpdateExtraAreaWidth]

void CodeEditor::updateLineNumberAreaWidth(int /* newBlockCount */)
{
    setViewportMargins(lineNumberAreaWidth(), 0, 0, 0);
}

//![slotUpdateExtraAreaWidth]

//![slotUpdateRequest]

void CodeEditor::updateLineNumberArea(const QRect &rect, int dy)
{
    if (dy)
        lineNumberArea->scroll(0, dy);
    else
        lineNumberArea->update(0, rect.y(), lineNumberArea->width(), rect.height());

    if (rect.contains(viewport()->rect()))
        updateLineNumberAreaWidth(0);
}

//![slotUpdateRequest]

//![resizeEvent]

void CodeEditor::resizeEvent(QResizeEvent *e)
{
    QPlainTextEdit::resizeEvent(e);

    QRect cr = contentsRect();
    lineNumberArea->setGeometry(QRect(cr.left(), cr.top(), lineNumberAreaWidth(), cr.height()));
}

//![resizeEvent]

//![cursorPositionChanged]

void CodeEditor::highlightCurrentLine()
{
    QList<QTextEdit::ExtraSelection> extraSelections;

    if (true || !isReadOnly()) {
        QTextEdit::ExtraSelection selection;

        QColor lineColor = QColor(Qt::yellow).lighter(160);

        selection.format.setBackground(lineColor);
        selection.format.setProperty(QTextFormat::FullWidthSelection, true);
        selection.cursor = textCursor();
        selection.cursor.clearSelection();
        extraSelections.append(selection);
    }

    setExtraSelections(extraSelections);
}

//![cursorPositionChanged]

//![extraAreaPaintEvent_0]

void CodeEditor::lineNumberAreaPaintEvent(QPaintEvent *event)
{
    QPainter painter(lineNumberArea);
//    painter.fillRect(event->rect(), Qt::lightGray);
    painter.fillRect(event->rect(), Qt::gray);
    painter.setFont(this->font());

    // 获取当前光标行号
    auto cursor = this->textCursor();
    auto cursor_block_num = cursor.blockNumber();

//![extraAreaPaintEvent_0]

//![extraAreaPaintEvent_1]
    QTextBlock block = firstVisibleBlock();
    int blockNumber = block.blockNumber();
    int top = qRound(blockBoundingGeometry(block).translated(contentOffset()).top());
    int bottom = top + qRound(blockBoundingRect(block).height());
//![extraAreaPaintEvent_1]

//![extraAreaPaintEvent_2]
    while (block.isValid() && top <= event->rect().bottom()) {
        if (block.isVisible() && bottom >= event->rect().top()) {
            QString number = QString::number(blockNumber + 1);
            if (blockNumber == cursor_block_num) {
//                painter.setPen(Qt::black);
                painter.setPen(Qt::yellow);
            } else {
//                painter.setPen(Qt::gray);
                painter.setPen(Qt::white);
            }
            painter.drawText(0, top, lineNumberArea->width(), fontMetrics().height(),
                             Qt::AlignRight, number);
        }

        block = block.next();
        top = bottom;
        bottom = top + qRound(blockBoundingRect(block).height());
        ++blockNumber;
    }
}
//![extraAreaPaintEvent_2]

